I. Field of the Invention
This invention relates to an electrical surge protection device for protecting electrical applicances from transient voltage surges. Specifically, the present invention is an electrical surge protection device adapted for removable, external mounting on the back side portion of any of various types of electrical outlets, such as standard electrical wall outlets.
II. Background Information
A variety of electrical surge protection devices for use in conjunction with or for inclusion within electrical outlets are known. Known or conventional electrical surge protection devices typically include surge protection components such as varistors. One type of conventional electrical surge protection device is the type illustratively disclosed in the following U.S. Patents: U.S. Pat. Nos. 4,480,891 to Wu; 4,500,160 to Bertsch; 4,420,214 to Wu; 4,075,676 and 4,071,872 to Phillips, Jr. Surge protection devices of the type disclosed in the above-cited patents are referred to as "intermediate" receptacles, so named because a device of this type is positioned between an appliance being protected and a front plate covering or front side portion of an electrical outlet.
More specifically, electrical appliances for which surge protection is to be provided are plugged into female contacts of an intermediate receptacle. Prongs of the intermediate receptacles are then plugged into the front of an electrical outlet to electrically connect the electrical appliances to the electrical outlet. The surge protection elements of the intermediate receptacle protect the electrical appliances from transient voltage surges in the voltage available at the electrical outlets.
Since a surge protection device of the intermediate receptacle variety is plugged into the front of an electrical outlet, one of these surge protection devices may be readily removed, at any time, from between an electrical appliance and the electrical outlet. An unknowing person may remove the device, or it may be removed inadvertently when the appliance is unplugged. Subsequently, an electrical appliance may be plugged directly into the wall outlet and used without the benefit of surge protection, and with the quite undesirable result that the appliance may be damaged by transient voltage surges.
Another type of conventional electrical surge protection device is illustratively disclosed in U.S. Pat. No. 4,217,619 to Tibolla. The type of surge protection device disclosed in Tibolla is designed to be mounted within an electrical outlet.
Surge protection devices which are mounted in wall outlets avoid the undesirable result which may be experienced with intermediate receptacle surge protection devices due to the fact that an intermediate receptacle may be readily removed from the front of an electrical outlet. That is, since the internally-mounted surge protection devices are internally mounted, and not plugged into the front of an electrical outlet, a surge protection device of this type cannot be readily removed from the front of the electrical outlet, and thus electrical appliances to be plugged into the electrical outlet can not be readily left unprotected from transient voltage surges. However, internal mounting of a surge protection device within an electrical outlet requires significant modification of the electrical outlet. For example, in order to make space for the surge protection device within the electrical outlet, it may be required to remove one of a pair of female receptacles of the electrical outlet as shown by Tibolla.
Another type of conventional surge protection device is disclosed in U.S. Pat. No. 4,439,807 to Reitz. The device disclosed in Reitz is a surge protector which is embodied in a triangular shaped housing. A threaded structure protrudes from the triangular housing, and this threaded structure is used to mount the surge protection device. The type of structure to which this surge protection device can be mounted must also be threaded. Accordingly, substantial modification of an electrical outlet is also required in order to mount the Reitz surge protection device to the electrical outlet.